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Frequently Asked Questions

What are UOP L and T?

UOP L and T powders and pastes are highly effective moisture scavengers for many plastics and coatings systems. These powders and pastes are molecular sieve zeolites; they have a crystal structure of the zeolite A type and the following chemical composition:

(M = alkali cation)

The zeolite structure consists of SiO4 and AlO4 tetrahedrons, which are linked to one another to form a three-dimensional network. The structure of this network is such that, inside the crystal lattice, large adsorption cavities are formed, which are connected to one another by channels of defined and absolutely identical diameter.

This diameter depends on the type of cation and is approximately 4 Ůgstrom units in the case of UOP T Powder and Paste and approximately 3 Ůgstrom units with UOP L Powder and Paste (1 Ůgstrom = 10-8 cm). The only molecules that can be adsorbed are those smaller than the diameter of the pores. This means water can be adsorbed, but the raw materials for plastics, coatings systems and adhesives cannot.


Samples of L Powder, L Paste, T Powder, and T Paste are available upon request. Samples come in one pound quantity.

Call 724-942-3090 for more information and pricing.


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Phone:  (724) 942-3090       
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UOP Powder or UOP Paste?

Either form can be used in the same systems. The paste form has the following advantages over the powder form:

- Easier to incorporate into any system

In the paste form, the solid has already been homogeneously dispersed. This means that no further dispersing energy is required during formulation; the paste can be dispersed quickly and absolutely homogeneously into the polyol component by simply stirring it in. This saves energy and machine hours!

- Easier to handle

A moisture scavenger naturally also adsorbs moisture from the air. UOP paste is prepared by adding the powder to hydrophobic castor oil. This prevents atmospheric moisture from entering the zeolite, which means that the paste adsorbs virtually no moisture at all during handling or if allowed to stand in the open air. Even if drums have been opened and are left by mistake overnight or for the weekend without a cover, the paste can still be used.

It has been taken into account when using the paste form that the castor oil itself acts as a polyol and, because of its OH groups, is incorporated into the polyurethane structure (OH content of castor oil: approximately 5%).


UOP T Powder and Paste have been successfully used in a wide variety of systems. UOP L Powder and Paste have the following additional advantages:

- Higher surface quality of coatings

Whereas UOP T, because of its structure, may still contain small amounts of adsorbed gas (N2, CO2), UOP L is gas free. This means that coatings and casting resins can cure without any defects.

- Stable pot life

The use of UOP T can, in certain two-pack systems and especially in the presence of short-chain polyether polyols, produce a shortening of the pot life. When UOP L is present, however, a pot life, once it has been set, remains completely stable even if it is stored for a long time before application. In the case of one-pack sealants, the use of UOP L leads to an improvement in the storage stability.

The UOP Powder and Paste is always added together with the fillers and pigments to A component (polyol component) of the system. UOP Powder and Paste adsorb water very quickly. Generally speaking the polyol component needs to stand for only one hour minimum, but preferably overnight, before curing can be carried out by adding the isocyanate component.